Method of side-cutting by turret punch press

ABSTRACT

A method of side-cutting by a turret punch press for improving working efficiency to a large extent. The method comprises a step in which a selected one (5 1 ) of a plurality of punch chips (5 1  to 5 4 ) arranged so as to be selectively hit in a punch assembly (1) provided on the upper turret (2) is used for side-cutting a workpiece (6) and the other step in which one end of a part to be cut into a punching piece with the side cutting is cut off by another punch chip (5 2 ).

FIELD OF THE INVENTION

The present invention relates to a method of side cutting by a turretpunch press for punching a plate form work.

BACKGROUND OF THE INVENTION

A turret punch press is designed to include an upper turret and a lowerturret and to punch a plate form workpiece between a punch provided onthe upper turret and a die provided on the lower turret.

On the other hand, it is possible to perform a side cutting for cuttinga workpiece by continuously moving the above-mentioned punch up anddown. As the side-cutting method, a method disclosed in JapaneseUnexamined Patent Publication No., 63-130228 is known.

The side cutting method disclosed in the above-identified publication isthat a punch provided with three stage edges, i.e. an upper edge, anintermediate edge and a lower edge, is driven up and down by means of ahydraulic cylinder for performing the side-cutting with the lower andintermediate edges, punching piece retained in a die is cut by means ofthe upper edge when a predetermined amount of the punching piece isretained, and the side cutting is again performed thereafter. The lower,intermediate and upper edges to be used for cutting are selected bycontrolling the stroke of the hydraulic cylinder.

However, in the above-mentioned side cutting method, since the punch isdriven through a substantially small stroke to perform the side cuttingwith the lower and the intermediate edges, a dimension to be cut in asingle stroke is relatively small and such as to require long processperiod. Furthermore, a saw-tooth like trace is frequently formed alongthe cutting surface to degrade the product quality.

Further, since the punching piece is cut while it is retained in apredetermined position in the die, a drooping can be created on theworkpiece to degrade the product quality when the side cutting processis performed along a relatively long dimension.

SUMMARY OF THE INVENTION

In view of the problems set forth above, it is a primary object of thepresent invention to provide a side cutting method which utilizes aturret punch press and which permits longer dimension in one stroke of apunch chip so as to significantly improve the processing efficiency.

Another object of the invention is to provide a side cutting methodwhich utilizes a turret punch press which can avoid the formation of aresidual drooping portion on the cut portion and further reduce theformation of a saw-tooth like trace along a steering surface.

In order to accomplish the above-mentioned primary object, there isprovided, in accordance with the first aspect of the present invention,a method of side-cutting by a turret punch press comprising the steps ofperforming a side cutting for a workpiece with predetermined one of aplurality of punch chips which are provided in a punch assembly mountedon an upper turret and adapted to be selectively impacted, and cuttingoff one end of a portion to be a punching piece by cutting in theside-cutting process by means of another one of punch chips.

In order to accomplish above-mentioned various objects, there isprovided, in accordance with the second aspect of the invention, amethod of side-cutting by a turret punch press comprising the steps ofperforming a side cutting for a workpiece with predetermined one of aplurality of punch chips which are provided in a punch assembly mountedon an upper turret and adapted to be selectively impacted, cutting offone end of a portion to be a punching piece by cutting in theside-cutting process by means of another one of punch chips, and againperforming the side cutting with the one of the punch chips continuingfrom a remained cut portion, and repeating a cycle consisted of the eachsteps.

The present invention achieves the following advantages. Namely, usingone of a plurality of punch chip provided in a punch assembly, theside-cutting process for the workpiece is performed, initially. Then,the punching piece formed by the side-cutting is cut off by means ofanother punch chip. Repeating the foregoing operation, the side-cuttingof the workpiece into the desired configuration is performed. Therefore,the length to be cut in one stroke of the punch chip can be longer thanthe conventional side-cutting method to significantly improve theworking efficiency. Also, upon cutting off of the punching piece, a partof the cut portion is left so that side-cutting is performedsubsequently with continuing from the cut portion. By this, it becomespossible to perform side cutting without forming the drooped trace.

In addition, with this method, since the length of side cutting in onestroke can be made longer, it can reduce the saw-tooth like trace to beformed on the shearing surface.

Above-mentioned and other objects of the present invention, aspects andadvantages will become clear to those skilled in the art with thefollowing descriptions and associated drawings illustrating preferredembodiment exemplarily shown in consistent with the principle of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood more fully from the detaileddescription given herebelow and from the accompanying drawings of thepreferred embodiment of the invention, which, however, should not betaken to be limitative to the invention but are for explanation andunderstanding only.

FIG. 1 is a fragmentary longitudinal section of a major portion of aturret punch press for implementing the preferred method according tothe present invention;

FIG. 2 is an illustration as viewed along an arrow II in FIG. 1;

FIG. 3 is an illustration as viewed along an arrow III in FIG. 1;

FIGS. 4 and 5 are illustrations showing operation of the methodaccording to the invention; and

FIGS. 6A through 6D, 7 and 8 are illustrations showing operations ofother side cutting methods of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A side cutting method according to the present invention will bediscussed hereinafter in greater detail with reference to theaccompanying drawings.

In the drawings, the reference numeral 1 denotes a punch assemblymounted on an upper turret 2 of a turret punch press, 3 denotes a diemounted on a lower turret 4. A side cutting process for a plate formworkpiece 6 can be performed between the punch chip 5 and the die 3 ofthe punch assembly 1.

The punch assembly 1 includes a cylindrical punch guide 7, as shown inFIG. 1. The punch chip 5 is disposed within the punch guide 7 forvertical sliding movement.

The punch chip 5 comprises a large diameter punch chip 5₁ having a body5a disposed within the punch guide 7 for vertical sliding movement, anda plurality of, such as three, smaller diameter punch chips 5₂, 5₃ and5₄ disposed in a plurality of guide holes 5b formed through the body 5afor vertical sliding movement. The punch chip 5₁ has a rectangular tipend, on which a cutting edge 5c with a lower face tapered in thevertical direction so that the side cutting process for a workpiece 6can be performed with the cutting edge 5c and a rectangular cutting slotformed in the die 3.

The punch chip 5₂ is arranged co-axially with the cutting edge 5c andhas a tip end, on which a square cutting edge 5d having the same widthto the cutting edge 5c is formed so that punching piece 6a can be cutoff by means of the cutting edge 5d.

The remaining punch chips 5₃ and 5₄ are arranged at both sides of thepunch chip 5₁ as shown in FIG. 2. Circular and triangular cutting edges5e and 5f are formed on the chip ends of the punch chips 5₃ and 5₄.

On the other hand, the punch chip 5₁ has an upper end portion havingsmaller diameter. The smaller diameter portion 5g fixedly mounts a punchhead 9, center of which is adapted to receive an impact by an striker14₁ discussed later. Between the punch head 9 and an upper plate 7aprovided on the upper end of the punch guide 7, a stripping spring 10formed of a resilient or an elastic body, such as a rubber, is disposedfor urging the punch chip 5₁ upwardly.

The upper ends of other punch chips 5₂ to 5₄ are extended around thesmaller diameter portion 5g and reach through openings 9a formed throughthe punch head 9 through through holes 10a defined in the strippingspring 10. The upper ends of the punch chips 5₂ to 5₄ are arrangedsubstantially in flush with the upper surface of the punch head 9.

Between spring seats 5h formed at positions slightly above theintermediate portions of respective punch chips 5₂ to 5₄ and the uppersurface of the body 5a of the punch chip 5₁, stripping springs 11comprising coil springs are disposed. With these stripping springs 11,respective punch chips 5₂ to 5₄ are biased upwardly.

On the other hand, at an impacting position of the turret punch press, aram 14 which is adapted to be driven vertically by means of a not showndrive mechanism. A plurality of strikers 14₁, 14₂, 14₃ and 14₄ areprovided on the lower surface of the ram 14 for projecting andcontracting with respect thereto.

The strikers 14₁ to 14₄ are arranged at corresponding positions to aplurality of punch chips 5₁ to 5₄ provided in the punch assembly 1. Bydriving the ram 14 vertically with selectively projecting the strikers14₁ to 14₄, the punch chips 5₁ to 5₄ corresponding to these strikers 14₁to 14₄ can be impacted.

By impact given by the strikers 14₁ to 14₄, one of the chips 5₁ to 5₄ isdriven downwardly to extend the cutting edges 5c. 5d, 5e and 5f providedat the tip ends thereof downward from the holes 15₁ to 15₄ of a stripperplate 15 provided on the lower end of the punch guide 7. Thus, as shownin FIG. 3, the cutting edge 5c, 5d, 5e and 5f can perform punching ofthe workpiece with the cutting slots 3a, 3b and 3c formed in the die 3at corresponding positions thereto.

It should be noted that, in the drawings, the reference numeral 20denotes a positioning key for positioning the punch chip 5 relative tothe punch guide 7, 21 denotes a positioning key for performingpositioning of the punch assembly 1 relative to the upper turret 2.

Next, discussion will be given for a process for side cutting of theworkpiece 6 using a die apparatus composed of the punch assembly 1 andthe die 3, with reference to FIGS. 4 to 8.

During side cutting of the workpiece 6, the workpiece 6 is initiallymoved by a clamp 22 for setting the side cutting start position of theworkpiece 6 at a punch position. The clamp 22 is designed to clamp theworkpiece 6 and move the latter relative to the punch assembly in per seknown manner. Then, the side cutting process is initiated by projectingthe striker 14₁ from the lower end of the ram 14 for impacting the punchchip 15₁.

By downward motion of the ram 14, the striker 14₁ impacts the punch head9 corresponding to punch chip 15₁. Thus, the punch chip 15₁ is moveddownwardly against the stripping spring 10 to extend the cutting edge 5cat the lower end of the punch chip 5₁ from the hole 15₁ of the stripperplate 15. Thus, the workpiece 6 is cut in the length l₁ between thecutting edge 5c and the die 3.

Subsequently, according to upward motion of the of the punch chip 5₁,the striker 14₁ is retracted. Then, the striker 14₂ necessary for thenext operation is projected and the punch chip 5₂ is impacted from theabove by downward movement of the ram 14, as shown in FIG. 5.

By this, the punch chip 5₂ is moved downwardly to cut off the punchingpiece 6a cut by the punch chip 5₁ m between the cutting edge 5d of thepunch chip 5₂ and the die 3. Thus, a rectangular hole of the length l₂is formed in the workpiece 6.

In this case, by making the vertical stroke of the ram 14 variable andthus making the vertical stroke of the punch chip 5₁ variable, thelength l₂ of the hole can be differentiated within a predeterminedrange.

It should be appreciated that although the punch chip 5₂ is used in theforegoing process for cutting off the slug, the punch chip 5₃ or 5₄ maybe used in place of the punch chip 5₂.

The foregoing is an example, in which the length l₁ is initially cut bythe punch chip 5₁ and subsequently, the punching piece 6a is cut off bythe punch chip 5₂ for forming the rectangular hole 6b in the length ofl₂. Conversely, an example shown in FIG. 7 is adapted to initially cut alength l₃ by making the vertical stroke of the ram 14 variable, andthen, as shown in FIG. 8, a length l₄ of the punching piece 6a is cutoff by the punch chip 5₂ with leaving the cut portion in the length l₅.Subsequently, the side cutting is continued following to the cutportion. With this process, it becomes possible to perform a sidecutting process without leaving a drooping portion while reducing thesaw-tooth like trace along the shearing surface, as shown in FIGS. 6A to6D.

Although the invention has been illustrated and described with respectto exemplary embodiment thereof, it should be understood by thoseskilled in the art that the foregoing and various other changes,omissions and additions may be made therein and thereto, withoutdeparting from the spirit and scope of the present invention. Therefore,the present invention should not be understood as limited to thespecific embodiment set out above but to include all possibleembodiments which can be embodies within a scope encompassed andequivalents thereof with respect to the feature set out in the appendedclaims.

I claim:
 1. A method of side-cutting by a turret punch press comprisingthe steps of:providing a plurality of punch chips in a single punchassembly mounted on an upper turret, each of said punch chips beingadapted to be individually and selectively impacted in a manner whichdrives them to their respective cutting positions; side-cutting aworkpiece with a predetermined one of said plurality of punch chips byimpacting the corresponding one of said plurality of punch chips so asto partially cut out a punching piece by cutting at least two parallelsides of said punching piece with a single stroke of said one punchchip, said partially cut out punching piece remaining attached to saidworkpiece at an end portion of said punching piece; and cutting off saidpunching piece from said workpiece by cutting said end portion of saidpartially cut out punching piece by completing the cutting produced bysaid side-cutting step using another one of punch chips.
 2. A method ofside-cutting using a turret punch press comprising the steps of:(a)providing a plurality of punch chips in a punch assembly mounted on anupper turret, each of said punch chips being adapted to be individuallyand selectively impacted; (b) performing a side-cutting of a workpiecewith a predetermined one of said plurality of punch chips by impactingthe corresponding one of said plurality of punch chips in a manner whichpartially cuts out a punching piece by cutting at least two parallelsides of said punching piece with a single stroke of said one punchchip, said partially cut out punching piece remaining attached to saidworkpiece at an end portion of said punching piece; and (c) cutting offsaid punching piece from said workpiece by cutting said end portion ofsaid partially cut out punching piece by completing the cutting by saidside-cutting using another one of said plurality of punch chips; andrepeating steps (a), (b) and (c) on the remaining portion of said workpiece.
 3. A process for performing side-cutting using a turret punchincluding an upper turret carrying a punch assembly and a lower turretcarrying a die, comprising the steps of:providing a first punch chip forperforming a side-cutting of a workpiece in said punch assembly carriedby said upper turret, said first punch chip being adapted to beselectively impacted for performing said side-cutting operation in amanner which partially cuts out a slug from said work piece; providingat least one second punch chip for cutting off said slug from theworkpiece in said punch assembly, said second punch chip being adaptedto be selectively impacted for performing said slug cutting offoperation independently of said first punch; performing a side-cuttingstep, in which an impact is applied to said first punch chip forside-cutting a predetermined length of said workpiece in a manner whichpartially cuts out a slug which is to be removed from said work piece bycutting at least two parallel sides of said slug with a single stroke ofsaid first punch chip; performing a slug cutting off step subsequent tosaid side-cutting step, in which an impact is applied to said secondpunch for cutting said slug completely free of said workpiece; andrepeating said side-cutting step and said slug cutting off step.
 4. Aprocess as set forth in claim 3, wherein application of impact for saidfirst and second punch chips is selectively performed by an impactingmeans including first and second impacting elements respectivelycorresponding to said first and second punch chips, which first andsecond impacting elements are movable between a working position and aresting position for impacting corresponding first and second punchchips, said process including a step of positioning said first impactingelement corresponding to said first punch chip at said working positionwhile maintaining said second impacting element at said resting positionin advance of application of impact in said side-cutting step and a stepof positioning said second impacting element corresponding to saidsecond punch chip at said working position while maintaining said firstimpacting element at said resting position in advance of said slugcutting off step.
 5. A process as set forth in claim 3, wherein thestroke of said first punch chip is variable within a predetermined rangefor varying said predetermined length for side-cutting in one stroke. 6.A turret punch press for side-cutting, comprising:an upper turretcarrying a punch assembly; a lower turret carrying a die; a first punchchip carried in said punch assembly, said first punch chip beingmovable, within a predetermined stroke range, toward and away from aworkpiece for which side-cutting is to be performed; at least one secondpunch chip carried in said punch assembly and movable, within apredetermined stroke range, toward and away from said workpiece forwhich side-cutting is to be performed; said punch assembly having afirst active condition for side-cutting, wherein said first punch chipis projected toward said workpiece beyond said second punch chip and asecond condition for removing a slug partially formed in the process ofside-cutting performed at said first condition of said punch assembly,in which said second punch chip is projected toward said workpiecebeyond said first punch chip; and impacting means for applying impact tosaid first and second punch chips, said first impacting means includinga first impacting element corresponding to said first punch chip, and asecond impacting element corresponding to said second punch chip; saidimpacting means having a first active condition for side-cutting, inwhich said first impacting element is projected toward said first punchchip beyond said second impacting element, and a second active conditionfor removing a slug formed in the process of side-cutting performed atsaid first active condition of said impacting means, in which saidsecond impacting element is projected toward said second punch chipbeyond said first impacting element; said impacting means being operableto alternately operate said first and second impacting elements forsequentially performing side-cutting process and slug removing process;said first punch chip having first and second generally parallel cuttingedges spaced apart a first distance for cutting two generally parallelsides of a slug to be removed from said workpiece; and said second punchchip having a third cutting edge extending generally transverse to saidfirst and second cutting edges of said first punch chip, said thirdcutting edge being disposed within a width of said first and secondcutting edges and having a length approximately equal to said firstdistance.
 7. A turret punch press as set forth in claim 6, wherein saidfirst punch chip is disposed in a first hollow punch guide and whereinsaid punch assembly further includes a second punch guide in which saidsecond punch is disposed.
 8. A turret punch press as set forth in claim6, wherein the magnitude of projection of said first impacting elementin said first active condition is variable for varying a length to becut through one stroke of side-cutting process.